Hit papers significantly outperform the citation benchmark for their cohort. A paper qualifies
if it has ≥500 total citations, achieves ≥1.5× the top-1% citation threshold for papers in the
same subfield and year (this is the minimum needed to enter the top 1%, not the average
within it), or reaches the top citation threshold in at least one of its specific research
topics.
Greenness in semi-arid areas across the globe 1981–2007 — an Earth Observing Satellite based analysis of trends and drivers
This map shows the geographic impact of Ulf Helldén's research. It shows the number of citations coming from papers published by authors working in each country. You can also color the map by specialization and compare the number of citations received by Ulf Helldén with the expected number of citations based on a country's size and research output (numbers larger than one mean the country cites Ulf Helldén more than expected).
This network shows the impact of papers produced by Ulf Helldén. Nodes represent research fields, and links connect fields that are likely to share authors. Colored nodes show fields that tend to cite the papers produced by Ulf Helldén. The network helps show where Ulf Helldén may publish in the future.
Co-authorship network of co-authors of Ulf Helldén
This figure shows the co-authorship network connecting the top 25 collaborators of Ulf Helldén.
A scholar is included among the top collaborators of Ulf Helldén based on the total number of
citations received by their joint publications. Widths of edges
represent the number of papers authors have co-authored together.
Node borders
signify the number of papers an author published with Ulf Helldén. Ulf Helldén is excluded from
the visualization to improve readability, since they are connected to all nodes in the network.
Hill, Joachim, et al.. (2010). Integrating MODIS-EVI and Gridded Rainfall/temperature Fields for Assessing Land Degradation Dynamics in Horqin Sandy Lands, Inner Mongolia (China).1 indexed citations
Tøttrup, Christian & Ulf Helldén. (2007). Long term NOAA-AVHRR GIMMS-NDVI - rainfall relationships and trends 1981 to 2003 for entire DeSurvey area of interest. Lund University Publications (Lund University).4 indexed citations
5.
Helldén, Ulf. (2005). CASE STUDIES OF DESERTIFICATION MONITORING. -A DISCUSSION OF EU INITIATIVES. Lund University Publications (Lund University). 195–203.1 indexed citations
6.
Helldén, Ulf, et al.. (1999). Desertification and global climate change – Little Ice Age desertification in Iceland?. Lund University Publications (Lund University).1 indexed citations
7.
Helldén, Ulf. (1991). Desertification - time for an assessment?. AMBIO. 20(8). 372–383.175 indexed citations
8.
Helldén, Ulf & Lars Eklundh. (1989). National Drought Impact Monitoring: a NOAA NDVI and Precipitation Data Study of Ethiopia. Lund University Publications (Lund University).26 indexed citations
9.
Helldén, Ulf. (1988). Desertification monitoring: is the desert encroaching?. 8–12.39 indexed citations
10.
Helldén, Ulf. (1987). An assessment of woody biomass, community forests, land use and soil erosion in Ethiopia. A feasibility study on the use of remote sensing and GIS-analysis for planning purposes in developing countries.35 indexed citations
11.
Helldén, Ulf. (1987). An assessment of woody biomass, community forests, land use and soil erosion in Ethiopia. A feasibility study on the use of remote sensing and GIS [geographical information system]-analysis for planning purposes in developing countries..15 indexed citations
12.
Helldén, Ulf. (1984). Drought impact monitoring. A remote sensing study of desertification in Kordofan, Sudan. Medical Entomology and Zoology.24 indexed citations
13.
Helldén, Ulf, et al.. (1982). The potential of Landsat MSS data for wood resources monitoring : a study in arid and semi-arid environment in Kordofan, the Sudan. Medical Entomology and Zoology.2 indexed citations
14.
Helldén, Ulf. (1980). A test of landsat-2 imagery and digital data for thematic mapping illustrated by an environmental study in northern Kenya, Lund University. Medical Entomology and Zoology.21 indexed citations
15.
Helldén, Ulf & Mark J. Stern. (1980). Monitoring land degradation in southern Tunisia: A test of LANDSAT imagery and digital data. NASA Technical Reports Server (NASA).4 indexed citations
Helldén, Ulf. (1978). Evaluation of Landsat-2 imagery for desertification studies in northern Kordofan, Sudan. 38. 40.2 indexed citations
18.
Helldén, Ulf, et al.. (1977). LANDSAT digital data for water pollution and water quality studies in Southern Scandinavia. NASA Technical Reports Server (NASA).1 indexed citations
Rankless uses publication and citation data sourced from OpenAlex, an open and comprehensive
bibliographic database. While OpenAlex provides broad and valuable coverage of the global
research landscape, it—like all bibliographic datasets—has inherent limitations. These include
incomplete records, variations in author disambiguation, differences in journal indexing, and
delays in data updates. As a result, some metrics and network relationships displayed in
Rankless may not fully capture the entirety of a scholar's output or impact.